The mammalian genomes express a large number of long noncoding RNAs (lncRNAs). Only a handful of them, however, have been studied. The known lncRNAs have diverse roles in the cell, mostly in the nucleus, such as chromatin remodeling, transcription, and RNA processing. Adipogenesis is the process that generates adipocytes from precursor cells, which have many implications for human diseases, such as diabetes and cardiovascular diseases. While regulation of protein-coding genes in adipogenesis has been well studied, the role of lncRNAs is completely unclear. We have sequenced the transcriptomes of human and mouse cells undergoing adipogenesis to an unprecedented depth. Our preliminary analysis indicates that a set of lncRNAs are highly regulated during adipogenesis, suggesting their functional roles in the process. In this grant, we plan to examine known and novel lncRNAs that are regulated in adipogenesis for their roles in differentiation of precursor cells into mature adipocytes.